Control Levels of Virtual Commissioning

Controls on the Simulation Model

During virtual commissioning, the previously generated sequence simulation is connected to the real control system. Three levels are generally available for this purpose:

  •     PLC / robot control level
  •     Material flow computer ("MFR") level
  •     Master computer / production control level

The simulation model always covers the level that is not part of the test setup. If, for example, the PLC logic is to be checked, the model covers only the sensor/actuator level; if the material flow computer level is to be checked, the model also includes the PLC logic. Mixed forms in which the PLCs of individual plant areas are present are also possible; missing areas are taken over by the model.

PLC / robot control level

Here the virtual system is connected to the real PLC and controlled by it. The actuator signals (control signals for motors, opening/closing of valves, proportional control of valves, ...) and control words of the PLC are interpreted and control the model. The latter sends back the sensor and feedback signals (light barriers, temperature sensors, barcodes, pulse encoder and encoder values, feedback signals of motors, limit switches, ...) to the PLC. There is no difference between model and real plant for the PLC software, the model behaves 100% like the real plant. Thus, the PLC logic can be tested before actually operating the plant.


    Phase 1: Preparation

  •     For graphical modeling of new and unavailable plant components within the simulation platform, CAD data from an early phase of the design is used. If not available or not required, abstract geometry blocks are used. Depending on the project requirements, PLC (real or virtual), robot controller, control panel and other components are connected to the virtual system. The programming of the first software modules of the respective control system is carried out, interference contours and functionality are checked.

    Phase 2: Implementation

  •     Here, assembly and implementation are carried out. For this purpose, the components simulated virtually so far (robots, conveyor technology, ...) are replaced by real components. In addition, the wiring of the system components and the first functional tests are carried out.

    Phase 3: Evaluation

  •     Real commissioning and evaluation. PLC and robot programming are completed, and the connection of components not yet connected to the plant control system is carried out. The control software is already highly mature, only a few interventions in the programming are required.


Material Flow Computer ("MFR") Level

During virtual commissioning at MFR level, the material flow computer and simulation model communicate at telegram level. The MFR sends orders to the system and queries status messages. For example, the MFR executes individual transport orders for the warehouse management system, monitors conveyor routes and passes the data to the PLC (the model). Here, the simulation can represent the control of each automated operating, conveying and also sorting element, check it and, if necessary, improve it before commissioning.

Master computer / production control level

Test of the scheduling system (communication between simulation model and host computer on telegram level).


  •     Mapping of the PLC logic within the simulation model.
  •     Definition of a communication interface based on telegrams exchanged between the simulator and the master computer.